Chromosome rearrangement of erythroblast transformation specific (ETS) family members in prostate cancer, similar to other translocation tumors, may represent a distinct subclass of prostate cancer, based on studies demonstrating varying morphologic features (Mosquera et al., J Pathol 2007; 212: 91-101), survival (Attard et al., Oncogene 2008; 27: 253-63; Cheville et al., J Clin Oncol 2008; 26: 3930-6; Demichelis et al., Oncogene 2007; 26: 4596-9), and a specific expression profile (Setlur et al., J Natl Cancer Inst 2008; 100: 815-25). Androgen-regulated genes account for the majority of the 5′ genomic regulatory promoter elements fused with ETS genes in prostate cancer (Tomlins et al., Nature 2007; 448: 595-9). For example, the promoter of the androgen-regulated transmembrane protease, serine 2 (TMPRSS2) gene is fused to the coding region of members of the ETS family of transcription factors, most commonly v-ets erythroblastosis virus E26 oncogene homolog (avian) (ERG) (Helgeson et al., Cancer Res 2008; 68: 73-80; Tomlins et al., Cancer Res 2006; 66: 3396-400; Han et al. Cancer Res 2008; 68: 7629-37). The presence of these fusion genes can serve as diagnostic markers and rational therapeutic targets for the treatment of prostate cancer and other cancer types. SLC45A3 (solute carrier family 45, member 3), also referred to as prostein, is a prostate-specific, androgen-regulated gene that has been shown to be a 5′ partner with ETV1 and ETV5 (Tomlins et al., Nature 2007; 448: 595-9; Helgeson et al., Cancer Res 2008; 68: 73-80). The majority of the cases demonstrating SLC45A3 rearrangement were seen in conjunction with either ERG (80%) or ETV1 (10%), but the 3′ partners for the remaining 10% of SLC45A3 in prostate cancers have not been identified. ELK4 (ETS-domain protein (SRF accessory protein 1)), a member of the ETS family of transcription factors, was recently described as a novel androgen receptor target in LNCaP cells promoting cell growth (Makkonen et al., Oncogene 2008; August 21; 27(36):4865-76. Epub 2008 May 12).